The hydrocarbon industry employs a variety of downhole tools during production and well workovers. A zonal isolation device is one such type of tool. Zonal isolation devices are used in a variety of settings to block or control the flow of fluids in a well bore. Examples of zonal isolation devices may include bridge plugs, fracture plugs, or any other device capable of separating pressure and flow zones within a well bore. Production zonal isolation devices seal off a portion of a well during production of hydrocarbons. Retrievable zonal isolation devices may be employed during well workovers when they are not intended to remain in the well during production. The retrievable zonal isolation device performs a number of functions, including but not limited to: isolating one pressure zone of a well bore formation from another, protecting the production liner or casing from reservoir pressure and erosion that may be caused by workover fluids, and eliminating or reducing pressure surging or heading.
Retrievable zonal isolation devices may be used during well workovers. During a typical well workover, a section of the well bore is isolated using a zonal isolation device, which may typically be a bridge plug. The isolated portion is then subjected to treatments intended to increase the flow of hydrocarbons from the well. In a typical well workover, several such isolated intervals may require treatment. Traditionally, a temporary bridge plug has been set to define an interval. After each treatment, the work string is removed to allow for the addition of another bridge plug to define the next interval. At the end of the workover, the bridge plugs are milled out. The rig time required to set multiple bridge plugs and thereafter remove the plugs can negatively impact the economics of the project, as well as add unacceptable complications and risks.
Traditional zonal isolation devices used during well workovers are set in place using rotational and longitudinal movement. The zonal isolation device may be run down on production tubing or coiled tubing to a desired depth in the well bore before being set. Conventional zonal isolation devices are then set using rotation, typically provided by rotating the tubing string at the wellhead. The rotation expands a set of slips that engage the inside of a production liner or casing. Following the setting of the slips with rotation, the weight of the tubing string is then set down on the bridge plug to fully engage the sealing elements. In this way, the zonal isolation device provides a seal between the zonal isolation device and the inside of a production liner or casing. While conventional production tubing possesses the mechanical strength and properties for applying a rotational force to the bridge plug, coiled tubing is not readily capable of being rotated. Further, highly deviated wells and extended reach wells may cause friction on conventional tubing that may prevent it from being used to provide an effective rotational or set down force on the bridge plug. In these wells and in wells in which the bridge plug is run on coiled tubing, only longitudinal force and hydraulic pressure may be used to set a bridge plug. Therefore, a need exists for a retrievable zonal isolation device that is capable of being set using longitudinal movement and hydraulic pressure and that may be set, unset, and reset multiple times during a single trip into the well bore.